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Artificial sweeteners vs sugar artificial sweeteners side effects effects of sugar on the brain sugar and the brain best sugar substitute

Artificial sweeteners vs sugar: How man-made sugars change your brain?


Visualise your favourite sweet treat. Is it a slice of indulging cake, a can of cold drink, or a big soft cookie? Regardless of your pick, your brain is loving the imagery. The relationship between sugar and the brain is evolutionary. Humans have evolved to love sugar, as it was needed for survival. Sugary foods also activate your reward and pleasure brain chemical, dopamine. Over the years, evidence added up about the health implications of excess sugar intake and the effects of sugar on the brain. This led to the creation of what scientists hoped would be the best sugar substitute: artificial sweeteners. Artificial sweeteners are much sweeter than sugar, which means a small amount is sufficient to impart sweetness to the food, at a much lower caloric value. These were made to satisfy the cravings of sugar without the added calories and health impact. Imagine enjoying that cake or cookie without the guilt. Are artificial sweeteners a dream come true or are they too good to be true? 

Artificial sweeteners are widespread 

Aspartame is an artificial sweetener that is 200 times sweeter than sugar. Since its approval as a safe ingredient, it can be found in over 6000 foods and has become the most common artificial sweetener used worldwide [1]. Aspartame is completely digested in your body. 50% of aspartame breaks down to a protein-building block and the other 50% produces harmful compounds that can impact brain health. Sucralose is another safe artificial sweetener which is 600 times sweeter than sugar, is heat-stable and passes through the body without absorption [2].

Despite their safety profile, long term studies of their effects on the brain are limited, and current evidence presents conflicting results. These five artificial sweeteners side effects might make you reconsider this invention:

1. Artificial sweeteners can affect your memory

Healthy participants were provided 4g of sucralose (4 sweetener sachets) per day for 6 weeks. They underwent memory and higher thinking tests before and after the consumption of sucralose. There was a 20% decrease in the memory scores after taking artificial sweeteners, in addition to a 16% decline in higher thinking skills [3]. A review of 8  studies highlighted the impact of aspartame on memory skills- increase in time taken to remember things, longer memory gaps and lower memory tests scores were reported. In some cases, the effects were seen within 8 days of aspartame intake [1]. Animal studies shed light on the possible cause of aspartame’s effect on memory tests. The harmful compounds produced after aspartame’s digestion can use up the protective compounds in the brain [4]. These compounds are also involved in memory functions. Since glucose is the brain's fuel of choice, replacing glucose with artificial sweeteners led to memory issues in animal studies [4].

2. Artificial sweeteners can lower mood and motivation

Upon digestion, 50% of aspartame is converted to a protein-building block called phenylalanine. Your brain chemicals serotonin and dopamine, which regulate your mood, sleep, motivation, and reward system, depend on protein building blocks called tryptophan and tyrosine for production. The brain has an entry system where protein building blocks compete to enter. Excess intake of aspartame increases the levels of phenylalanine. This competes with tryptophan and tyrosine and limits their entry into the brain [5]. Low levels of these will lead to low production of serotonin and dopamine. An animal study found that a high dose of aspartame for 2 weeks decreased serotonin levels by 50% and dopamine levels by almost 40% [4].

3. Artificial sweeteners produce harmful compounds in the brain

The other 50% of aspartame produces harmful compounds upon digestion. These compounds activate the inflammatory process in the brain which can cause brain cell damage. It also affects the protective layer of brain cells. An animal study where aspartame was provided within acceptable limits for 45 days found that long term intake produced harmful compounds in the brain [6]. The damage was higher when the diet was low in protective compounds that can fight inflammation. In another study, when a high dose vitamin C was provided with aspartame, the level of damage was significantly lower [7].

4. Artificial sweeteners increase stress response

Aspartame increases the production of stress hormone, cortisol. Production of harmful compounds and disrupting the balance of brain chemicals like serotonin and dopamine contribute to increased cortisol levels [5]. Aspartame and sucralose were found to induce stress response in the coordination centre of your brain [8]

5. Artificial sweeteners increase headaches

A review of 5 studies reported that aspartame intake either increased the intensity of headaches or caused headaches [1]. Even 2 weeks of aspartame intake within acceptable limits was associated with an increase in headaches. Headaches disappeared after 10 days of aspartame avoidance [9]. Possible explanation for this was increased stress response, activating inflammatory compounds and low serotonin levels [1].

Your best bet at protecting brain health is to lower your intake of both sugar and artificial sweeteners. Reach for natural sweet sources like fruits and incorporate spices like cinnamon to impart sweetness to the food. This benefits your taste buds and your brain.


  1. Choudhary, A. K. & Lee, Y. Y. (2018) Neurophysiological symptoms and aspartame: What is the connection?, Nutritional Neuroscience, 21:5, 306-316
  2. Basson, A. R. et al. (2021). Artificial Sweeteners: History and New Concepts on Inflammation. Frontiers in nutrition8, 746247.
  3. Sagrario López-Meza, M. et al. (2022) The impact of nutritive and non-nutritive sweeteners on the central nervous system: preliminary study, Nutritional Neuroscience, 25:8, 1623-1632
  4. Abdel-Salam, O. M. et al. (2012). Studies on the effects of aspartame on memory and oxidative stress in brain of mice. European review for medical and pharmacological sciences16(15), 2092–2101.
  5. Choudhary, A. K., & Lee, Y. Y. (2018). The debate over neurotransmitter interaction in aspartame usage. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia56, 7–15.
  6. Iyaswamy, A. et al. (2018). Oxidative stress evoked damages leading to attenuated memory and inhibition of NMDAR-CaMKII-ERK/CREB signalling on consumption of aspartame in rat model. Journal of food and drug analysis26(2), 903–916.
  7. IBRAGIĆ-Emir, S. (2021). Artificial sweeteners elicit oxidative stress in rat brain and development of microcytic anemia: Promising protective effects of vitamin C. Journal of Research in Pharmacy, 25(2)(25(2)), pp.117–123. 
  8. Park, S. et al. (2019). Non-nutritive Sweeteners Induce Hypothalamic ER Stress Causing Abnormal Axon Outgrowth. Frontiers in endocrinology10, 876.
  9. Johns D. R. (1986). Migraine provoked by aspartame. The New England journal of medicine315(7), 456.

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